KR101083173B1 - Copolymer comprising alkene, acrylate and styrene, and optical film comprising the same - Google Patents

Abstract

The present invention provides a copolymer comprising at least one alkene monomer, at least one acrylate monomer and at least one styrene monomer and a method for producing the same. The present invention also provides an optical film including the copolymer, a polarizing plate and an image display device including the optical film.

Alkenes, Acrylate, Styrene, Optical Film

Description

Copolymers containing alkenes, acrylates and styrene, and optical films comprising the same {COPOLYMER COMPRISING ALKENE, ACRYLATE AND STYRENE, AND OPTICAL FILM COMPRISING THE SAME}

The present invention relates to novel copolymers and methods for their preparation. More specifically, the present invention has excellent transparency, excellent toughness, excellent mechanical properties, negative birefringence, excellent adhesion, and a novel copolymer applicable to various optical materials and its The present invention relates to a manufacturing method, an optical film including the copolymer, and a polarizing plate and an image display device including the optical film.

1-alkenes, especially ethylene, when copolymerized with alkyl (meth) acrylate comonomers can form polymers with different physical properties not obtainable from simple polyethylene. For example, some properties, such as adhesion, low temperature toughness, and the like, can be significantly improved as the content of comonomer (s) increases. Therefore, the development of copolymers incorporating such 1-alkenes and other comonomers has been the subject of much research.

Ethylene and alkyl acrylates or ethylene and alkyl methacrylate copolymers have generally been obtained in high temperature, high pressure reactions. Therefore, it is disclosed that the reaction is carried out by simultaneously adding ethylene and an acrylic monomer under harsh conditions of 1000 atm or more and 100 ° C. or more using a tubular reactor or an autoclave reactor, and the polymer obtained under such conditions is an acrylic monomer which is a polar monomer based on ethylene. Monomers are copolymerized polymerized in the range of 3 to 35%.

However, in order to implement such high temperature and high pressure conditions, an additional device is required for the safety of an operator such as a primary compressor, a secondary compressor, and a special reactor. In addition, due to harsh process conditions, many constraints are required to change the composition of the copolymer in a desired direction.

And the ethylene-based copolymer prepared by the conventional method is only a degree containing a slight polar group. That is, since the content of the polar monomer was not high, the crystallinity of the polyethylene remained in the copolymer, and the use as an optical material such as a transparent film was restricted. Therefore, the polymer obtained by the high temperature and high pressure method in the conventional tubular reactor or autoclave eventually had to focus on the development of a product that does not significantly affect the transparency.

Therefore, it is required to develop a new polar copolymer production method capable of producing a copolymer having high crystallinity without high crystallinity while avoiding harsh polymerization conditions at high temperature and high pressure.

On the other hand, the method of copolymerizing a vinyl monomer to an olefin using a metal complex catalyst has been known. However, due to the high affinity for the oxygen of the metal, the metal complex catalyst based on the initial transition metal and the lanthanide-based metal has a disadvantage of being easily contaminated by the functional group (C = O) of the polar vinyl monomer. It has been reported that copolymerization of alkyl acrylates and olefins is possible in metal complex catalyst systems based on some later transition metals, but the olefin content is still significantly high.

Controlled radical polymerization is an alternative method to overcome the shortcomings of the metal complex catalyst polymerization method in which the metal complex catalyst is contaminated by oxygen present in the monomer and the activity is lowered and a polymer having a low polar group content is obtained. ) Has been proposed. When copolymerizing an olefin and a polar vinyl monomer by ATRP (Atom Transfer Radical Polymerization) which is a typical polymerization method of controlled radical polymerization, the content of the polar vinyl monomer is obtained higher than the olefin content in contrast to the metal complex catalyst polymerization method. That is, it is possible to synthesize a random copolymer in which the olefin content is controlled to some extent according to the polymerization conditions. However, when ATRP is used, it takes a long time to obtain a high molecular weight and there is a limit that the olefin content is maintained at a low level. The 1-alkene-acrylate copolymer is suitable for use as an optical material because of its high transparency, but in order to be used for this purpose, the 1-alkene-acrylate copolymer should be excellent in heat resistance to prevent deformation due to heat generated during the manufacturing process and operation of the optical device. do. Therefore, development of a new copolymer capable of improving physical properties such as heat resistance is required.

On the other hand, the polymer material used for the retardation film has positive or negative birefringence. Two kinds of polymers having different polarization anisotropy in the molecule are optically isotropic in the unstretched state, and neither exhibits birefringence, but they show positive or negative birefringence by stretching of the film. Here, the increase in the polarization in the molecular chain chain axis direction by stretching is defined as a material showing positive birefringence, and the increase in the polarization in the direction perpendicular to the molecular chain chain axis is a material showing negative birefringence. Is defined.

 Polycarbonate (PC) and cyclic olefin resin currently used for retardation films are positive birefringent materials.

On the other hand, polymethyl methacrylate (PMMA) and polystyrene (PS) are known as positive birefringent materials, but they have brittle characteristics and insufficient film formability. Therefore, it is hard to reach practical use as a film for LCDs, and the extending | stretching of a PC film to a thickness direction by a special method, or the PC film which introduce | transduced the fluorene frame | skeleton etc. are newly proposed.

However, polystyrene does not always have positive birefringence. For example, if the phenyl group lies parallel to the molecular chain axis, it has positive birefringence and negative birefringence when the phenyl group is positioned at right angles to the molecular chain axis.

Polystyrene is one of the few polymers that can have negative birefringence, but has a brittle characteristic, which has the disadvantage of being broken during film forming.

The present invention has excellent transparency, excellent toughness, excellent mechanical properties, negative birefringence, excellent adhesiveness to materials such as metal, and can be applied to various optical materials It aims to provide.

In addition, the present invention can prepare a copolymer in which the appropriate amount of comonomers are polymerized required for the physical properties required even in the mild reaction conditions, the catalyst can be recovered and reused to ensure economic efficiency, and impurities in the polymer It is an object to provide a method for producing a copolymer that can be minimized.

In addition, an object of the present invention is to provide an optical film comprising the copolymer and a polarizing plate and an image display device including the optical film.

In order to achieve the above object, the present invention comprises 0.1 to 30 mol% of at least one alkene monomer, 30 to 99 mol% of at least one acrylate monomer and 0.1 to 50 mol% of at least one styrene monomer. It provides a copolymer.

The present invention also provides 0.1 to 30 mol% of at least one alkene monomer, 30 to 99 mol% of at least one acrylate monomer and 0.1 to 50 mol% of at least one styrene monomer in the presence of Lewis acid or metal oxide. It provides a method for producing a copolymer comprising the step of polymerizing with a radical polymerization initiator under.

The present invention provides an optical fiber comprising a copolymer comprising 0.1 to 30 mol% of at least one alkene monomer, 30 to 99 mol% of at least one acrylate monomer and 0.1 to 50 mol% of at least one styrene monomer. Provide a film.

In addition, the present invention includes a polarizer and a protective film provided on at least one side of the polarizer, the protective film is 0.1 to 30 mol% of at least one alkene monomer, 30 to 99 mol% of at least one acrylate monomer And it provides an optical film comprising a copolymer comprising at least one styrene-based monomer of 0.1 to 50 mol%.

In addition, the present invention provides an image display device including the optical film or the polarizing plate.

The copolymer according to the present invention includes a styrene monomer and may have a negative birefringence, and also includes an alkene monomer in addition to the styrene monomer, thereby providing excellent toughness and thus excellent mechanical properties. It has excellent optical properties such as transparency, and excellent adhesion to a material such as metal by the functional group of the acrylate monomer is advantageous when used as a laminated film. In addition, the method of preparing a copolymer according to the present invention can produce a copolymer in which an appropriate amount of alkene monomer is required for the required physical properties even under mild reaction conditions by using Lewis acid or a metal oxide, and when a metal oxide is used. It is possible to recover and reuse, thereby securing economic feasibility, and to solve the problem of impurities in the polymer, thereby producing a polymer of high purity.

Hereinafter, the present invention will be described in detail.

The copolymer according to the invention is characterized in that it comprises an alkene monomer, an acrylate monomer and a styrene monomer. In the present invention, the content of the alkene monomer, acrylate monomer and styrene monomer is preferably 0.1 to 30 mol%, 30 to 99 mol% and 0.1 to 50 mol%, respectively.

In the present specification, that the copolymer according to the present invention includes an alkene monomer, an acrylate monomer and a styrene monomer means that the copolymer according to the present invention is formed by polymerizing the monomers, and for convenience, terms of monomers The structure is expressed, and in fact, it is easily understood by those skilled in the art that the double bond of monomers does not exist in the main chain chain of the copolymer of the present invention as it is.

The glass transition temperature (Tg) of the copolymer according to the present invention is preferably in the range of 80 ~ 220 ℃. In addition, the copolymer according to the present invention preferably has a number average molecular weight of 5,000 to 400,000 and a weight average molecular weight of 10,000 to 800,000. In addition, it is preferable that the copolymer of the present invention has a temperature (Td ₅₀ ) at which 50% of its initial weight is decomposed within a range of 300 to 550 ° C.

In the present invention, the alkene monomer is not particularly limited and may include alkenes such as 1-alkene having a double bond at the end of the carbon chain, 2-alkene having a double bond in the middle of the carbon chain, 3-alkene and the like. Can be. It may also include cyclic olefins.

Examples of 1-alkenes include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and the like. Examples of the alkenes having a double bond in the middle of the carbon chain include 2-butene, 2-pentene, 2-hexene, 3-hexene, 2-heptene, 2-octene, 2-nonene and the like. Examples of the cyclic olefin include norbornene or norbornene-based derivatives, and may be represented by the following Chemical Formula 1.

In Chemical Formula 1,

m is an integer from 0 to 4;

R ₁ , R ₂ , R ₃ and R ₄ each independently represent a polar functional group or a non-polar functional group, or R ₁ and R ₂ , or R ₃ and R ₄ are connected to each other to form an alkylidene group having 1 to 10 carbon atoms Alternatively, R ₁ or R ₂ may be linked to any one of R ₃ and R ₄ to form a saturated or unsaturated aliphatic ring having 4 to 12 carbon atoms, or an aromatic ring having 6 to 24 carbon atoms.

In Chemical Formula 1, the nonpolar functional group is hydrogen; halogen; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkyl having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkenyl of 2 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkynyl having 3 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Cycloalkyl having 3 to 12 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Or halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy Aryl having 6 to 40 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Aralkyl having 7 to 15 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy.

In Chemical Formula 1, a polar functional group includes a polar group including at least one of oxygen, nitrogen, phosphorus, sulfur, silicon, and boron.

이 있다.

There is this.

In the polar functional groups, R ₅ is the same as or different from each other, and each independently halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, Linear or branched alkylene having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkenylene having 2 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkynylene having 3 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Cycloalkylene having 3 to 12 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Arylene having 6 to 40 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Aralkylene having 7 to 15 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Alkoxylene having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Or halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy , Carbonyloxyylene having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy,

R ₆ , R ₇ and R ₈ are the same as or different from each other, and each independently hydrogen; halogen; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkyl having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkenyl of 2 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Linear or branched alkynyl having 3 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryl oxy, Cycloalkyl having 3 to 12 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Aryl having 6 to 40 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Aralkyl having 7 to 15 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy, Alkoxy having 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl, and siloxy; Or halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, alkoxy, haloalkoxy, carbonyloxy, halocarbonyloxy, aryloxy , Carbonyloxy of 1 to 20 carbon atoms unsubstituted or substituted with one or more substituents selected from haloaryloxy, silyl and siloxy,

p is an integer from 1 to 10.

In the present invention, when the norbornene compound is used as the cyclic olefin monomer, especially the norbornene compound is 5-ethylester-2-norbornene, t-butyl-5-norbornene-2-carboxylate (NB-TBE) , Methyl-5-norbornene-2-methyl-2-carboxylate (Nb-MMA), 5-methylene-2-norbornene, norbornene, and 5-n-butyl-2-norbornene More preferably one or more.

The content of the alkene monomer in the copolymer is 0.1 to 30 mol%, preferably 10 to 30 mol%. If the polymer is composed of only monomers including polar groups without alken monomers, there is a problem of brittleness when the film is formed. In particular, the content of the alkene monomer in the copolymer of 10 mol% or more is less prone to breakage when applied to the laminated film of the optical material.

In the present invention, the acrylate monomer is sufficient as long as it has a compound having a double bond between the carbonyl group of the ester group and the conjugated (conjugated) carbon and its substituent is not particularly limited. The acrylate-based monomers described herein are to be understood to include not only acrylates but also acrylate-based derivatives, and include concepts such as alkyl acrylates, alkyl methacrylates, alkyl butacrylates, and the like.

Specifically, examples of the acrylate-based monomer include a compound represented by the following formula (2):

In Chemical Formula 2,

R ₁₁ , R ₁₂ and R ₁₃ are the same as or different from each other, and each independently represent a hydrogen atom, a monovalent hydrocarbon group having 1 to 30 carbon atoms which may include a hetero atom; R ₁₄ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

As another example, the acrylate monomer may be an alkyl acrylate including a straight or branched alkyl group having 1 to 12 carbon atoms of alkyl, or an alkyl methacrylate including a straight or branched alkyl group having 1 to 12 carbon atoms of alkyl. Or alkyl butyacrylate containing a straight or branched alkyl group having 1 to 12 carbon atoms of alkyl.

The content of the acrylate monomer in the copolymer is 30 to 99 mol%, preferably 35 to 99 mol% or 40 to 99 mol%, more preferably 50 to 99 mol% or 50 to 95 mol%, most Preferably it is 50-90 mol%.

When the content of the acrylate-based comonomer, which is the polar monomer, increases, it is possible to prevent crystallinity, which is inherent in 1-alkenes such as alkenes, in particular ethylene, to prepare an amorphous copolymer. Such amorphous 1-alkene-acrylate-based copolymers were difficult to manufacture by the prior art. The amorphous copolymer can be used as an optical material because of its high transparency and excellent adhesiveness. In particular, the amorphous copolymer has many polar functional groups, and thus has excellent adhesion to metals, and thus is advantageous for application to electrical devices.

In the reaction, when the amount of the acrylate-based comonomer is less than 30 mol% based on the total amount of monomers, there is a problem in bonding and transparency, and when it exceeds 99 mol%, there is a problem of brittleness. In addition, in order to apply the copolymer to the laminated film for an optical material, the amount of the acrylate-based monomer is preferably adjusted to 95 mol% or less, more preferably 90 mol% or less in order to alleviate the fracture property during film formation.

In the present invention, the styrene monomer includes both styrene and styrene derivatives. Styrene derivatives include styrene substituted with C _1-6 alkyl or halogen. Specifically, methyl styrene, ethyl styrene, propyl styrene, butyl styrene, pentyl styrene, hexyl styrene, fluoro styrene, styrene chloride and the like are preferable, but not limited to these examples.

The content of the styrene monomer in the copolymer is 0.1 to 50 mol%, preferably 0.1 to 30 mol%. When such a styrene monomer is introduced as a component of the copolymer, the copolymer can have a negative birefringence.

In the copolymer according to the present invention, when the molar ratio of the repeating units derived from the alkene monomer, the acrylate monomer and the styrene monomer is a, b and c, respectively, a = 0.001 to 0.3, b = 0.3 to 0.99, c = It is preferable that it is 0.001-0.5.

The copolymer may be a random copolymer, in which case it may be represented by Formula 3 and the substituent may include various repeating units. The copolymer may also include some blocks as long as they maintain transparency. It is preferable that the copolymer according to the present invention maintain transparency of 80% or more in light transmittance during film formation.

The copolymer has a glass transition temperature (Tg) in the range of 80 to 220 ° C, preferably in the range of 100 to 220 ° C. In order for the copolymer to be effectively used for an optical material, the copolymer preferably has a glass transition temperature of 100 ° C. or higher. In addition, the copolymer preferably has a number average molecular weight in the range of 5,000 to 400,000 or a weight average molecular weight in the range of 10,000 to 800,000, and the temperature (Td50) at which 50% of the initial weight of the copolymer is decomposed is 350 to 550 ° C. It is desirable to have a range.

The copolymer described above has a very high content of polar groups, so that the crystallinity of alkenes such as ethylene does not exist. Thus, the copolymer is transparent even after being processed into a polymer film, and has excellent adhesion to a material such as a metal. The film can have negative birefringence, and brittleness can be improved by the presence of an alkene monomer.

The alkene monomer-acrylate monomer-styrene monomer copolymer described herein may not only be composed of one alkene monomer, one acrylate monomer and one styrene monomer as its monomer component. At least one of the alkene monomers, acrylate monomers and styrene monomers may be composed of two or more kinds. In addition, without departing from the scope of the physical properties of the polymer and the object of the present invention, it may further comprise a comonomer. Examples of the comonomers include maleimide, methyl maleimide, ethyl maleimide, butadiene and the like.

The copolymer may be prepared by a method including polymerizing an alkene monomer, an acrylate monomer, and a styrene monomer with a radical polymerization initiator in the presence of a Lewis acid or a metal oxide.

The metal oxide is conceptually included in the Lewis acid because it serves as a Lewis acid which provides an acid site in the polymerization reaction. However, compared to other Lewis acids in general, there is no change in structure or composition substantially after the polymerization reaction, and thus, there is an additional advantage that not only can be easily separated but also reused. It will be referred to as an oxide or a composite metal oxide.

The metal oxide is preferably a compound represented by the following formula (3):

M _x N _y O _z

In Chemical Formula 3,

M represents at least one selected from the group consisting of alkaline earth metals, transition metals, group 13, and group 14 metals;

N represents a Group 5 or 6 atom;

O represents an oxygen atom;

x, y and z are values determined by the oxidation state of M and N,

x> 0, y> 0, and z> 0.

More specifically, the metal oxide is aluminum oxide (Al ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), zinc oxide (ZrO ₂ ), hafnium oxide (HfO ₂ ), silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ), cesium oxide (CeO ₂ ), dysprosium oxide (Dy ₂ O ₃ ), erbium oxide (Er ₂ O ₃ ), europium oxide (Eu ₂ O ₃ ), gadolinium oxide (Gd ₂ O ₃ ), Holmium oxide (Ho ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), ruthetium oxide (Lu ₂ O ₃ ), neodymium oxide (Nd ₂ O ₃ ), praseodymium oxide (Pr ₆ O ₁₁ ), samarium oxide (Sm ₂ O ₃ ), terbium oxide (Tb ₂ O ₃ ), thorium oxide (Th ₄ O ₇ ), thorium oxide (Tm ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), tin oxide (SnO), and titanium oxide ( Metal oxides such as TiO ₂ ), dysprosium aluminate (Dy ₃ Al ₅ O ₁₂ ), yttnium aluminate (Y ₃ Al ₅ O ₁₂ ), aluminum titanate (Al ₂ O ₃ TiO ₂ ), aluminum silicate ( 3Al ₂ O ₃ · 2SiO ₂ ), calcium titanate (CaTiO ₃ ), calcium zirconate (CaZrO ₃ ), iron Selected from the group consisting of complex metal oxides such as titanate (FeTiO ₃ ), magnesium aluminate (MgOAl ₂ O ₃ ), cesium aluminate (CeAl ₁₁ O ₁₈ ), Al ₂ (SO ₄ ) ₃ , and AlPO ₄ It is preferred that there is at least one.

The metal oxide can be recovered to near 100% even by a physical method using only a filtration device, and since the recovered metal oxide can be used for polymerization again, it is not only economical but also high-purity copolymer can be obtained. There is an advantage. The recovered metal oxide can generally be reused about 20 times.

The Lewis acid includes at least one metal selected from the group consisting of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, boron, aluminum, yttrium, zirconium, niobium, molybdenum, cadmium, rhenium and tin. It is preferably a Lewis acid formed by including a cation, and is composed of a halide, triflate, HPO ₃ ^2- , H ₃ PO ^2- , CF ₃ COO ⁻ , C ₇ H ₁₅ OSO ^2-, and SO ₄ ^2- It is preferable to include at least one anion selected from the group. More specifically, it is preferable that they are aluminum trichloride, scandium triflate, zinc triflate, copper triflate, trifluoroboron, a mixture of two or more thereof.

In the method of preparing the copolymer, the metal oxide or the Lewis acid is preferably used in an amount of 0.01 to 200 mol% based on the acrylate comonomer.

By using the metal oxide or Lewis acid, it is possible to appropriately control and control the content of the monomers contained in the repeating unit in the copolymer produced according to the required physical properties. Particularly when the alkene monomer present in the gas phase under the reaction conditions such as ethylene or propylene is partially dissolved in the solvent to participate in the polymerization reaction, the metal oxide or Lewis acid is polymerized in an appropriate amount of the alkene monomer necessary for the required physical properties of the copolymer prepared. It may serve to control as possible, and also serves to make the polymerization reaction at a low temperature low pressure compared to the prior art.

It is preferable that it is a peroxide, an azo compound, etc. as said radical polymerization initiator. More specifically, examples of the peroxide compound include hydrogen peroxide, decanonyl peroxide, t-butyl peroxy neodecanoate, t-butyl peroxy pivalate, 3,5,5-trimethyl hexanoyl peroxide, diethyl peroxide t-butyl peroxy-2-ethyl hexanoate, t-butyl peroxy isobutyrate, benzoyl peroxide, t-butyl peroxy acetate, t-butyl peroxy benzoate, di-t-butyl peroxide, t Amyl peroxy neodecanoate, t-amyl peroxy pivalate, t-amyl peroxy-2-ethyl hexanoate, 1,1,3,3-tetramethyl butyl hydroperoxide, alkali metal persulfate, Perborate and percarbonate, and examples of azo compounds include azo compounds such as 2,2'-azo-bis (isobutyronitrile) (AIBN) (2,2'-azo-bis (isobutyronitrile)). Can be mentioned. Preferred initiators are azo compounds. Mixtures of such initiators may also be used.

The radical polymerization initiator can be added to the reaction stream in any suitable manner, such as in pure form, in dissolved form in a suitable solvent and / or in admixture with a monomer or comonomer feed stream. The radical polymerization initiator used in preparing the copolymer is preferably added in the range of 0.01 to 10 mol% based on the acrylate monomer, but is not necessarily limited thereto, and may be appropriately used if necessary.

The polymerization of the copolymer is preferably carried out in a solvent, in particular an organic solvent. Examples of such solvents are preferably, but not necessarily limited to, one or more solvents selected from the group consisting of toluene, chlorobenzene, n-hexane, heptane, tetrahydrofuran, ether, methanol, ethanol, chloroform, and methylene chloride. . That is, if the solvent can be used in the technical field of the present invention is not particularly limited.

In the polymerization reaction, since the acrylate monomer and the styrene monomer are generally present in the liquid phase under the reaction conditions, they are dissolved in a solvent and participate in the polymerization reaction. Therefore, the reaction pressure is not particularly limited as long as the monomers included in the aforementioned copolymer may exist in the liquid phase under the reaction conditions.

On the other hand, since the alkene monomer is generally present in the gaseous state under the reaction conditions, especially in the case of ethylene and propylene, in order to contain the alkene monomer in an appropriate amount in the repeating unit of the copolymer of the present invention, the reaction conditions under pressure are required. If the alkene monomer is present in the liquid phase under the reaction conditions, the reaction pressure is not particularly limited.

The polymerization reaction is carried out under mild conditions of 200 atm and 150 ° C or less, preferably 50 atm or less and 100 ° C or less, unlike the prior art which requires harsh reaction conditions of at least 1000 atm and at least 100 ° C and high temperature and high pressure. The process can be simple, and the physical properties of the copolymer produced can be easily controlled. In addition, the metal oxide is particularly excellent in water safety, efficient and recyclable.

Specifically, the reaction conditions for the polymerization of the copolymer, when the alkene monomer is gaseous in the reaction conditions, the polymerization reaction is preferably made at a pressure of 5 to 200 atm and temperature conditions of 30 to 150 ℃, particularly preferably The reaction is carried out at a pressure of 20 to 50 atm and a temperature of 50 to 80 ℃.

If the pressure is less than 5 atm, there is a problem that the alkene content is lowered, if the pressure exceeds 200 atm it is necessary to install additional equipment in the process. In addition, when the temperature is less than 30 ° C, there is a problem that the initiator is not activated, and when it exceeds 150 ° C, there is a problem of excessive unreacted monomer generation and process control.

One specific embodiment of the present invention uses an ethylene or propylene as an alkene monomer, methyl methacrylate or methyl acrylate as an acrylate monomer, styrene as a styrene monomer, and aluminum oxide as a metal oxide. The polymerization is carried out using AIBN as a polymerization initiator at a temperature of 50 to 80 ° C.

The copolymers according to the invention described above can be used particularly suitably for the production of optical films. The copolymer according to the present invention may have a negative birefringence, and also have excellent optical properties such as transparency, excellent toughness and thus mechanical properties, and excellent adhesion to materials such as metals. Therefore, the optical film including the copolymer is suitable for use as a laminated film such as a polarizing plate because of excellent optical and mechanical properties and excellent adhesion. In particular, it is possible to provide an optical film having a negative birefringence without breaking problems in film formation as in the prior art. The optical film including the copolymer may be prepared as a polarizing film through post-treatment with a retardation compensation film having a birefringence and an iodine solution, and may be used as various other optical films.

The present invention also provides an optical film comprising the copolymer described above.

The method for producing the optical film according to the present invention using the copolymer described above is not particularly limited, and for example, a melt extrusion method, a calender film forming method, a solution cast film forming method, or the like can be used. The melt extrusion method is a method in which a copolymer is heated and melted in a cylinder, pressurized with a screw, and then discharged out from a die such as a T die. Referring to the melt extrusion temperature, the extruder internal temperature is 230 ° C, 240 ° C, 240 ° C, 245 ° C from the extruder inlet, and the die temperature is preferably 250 ° C. The said solution cast film forming method is a method of manufacturing a copolymer resin solution with an organic solvent, then forming into a film, drying a solvent, and winding up.

 In order to manufacture the optical film, general additives such as plasticizers, lubricants, impact modifiers, stabilizers, ultraviolet absorbers, and the like may be added to the copolymer resin. In particular, when the optical film according to the present invention is used as a protective film of the polarizer, in order to protect the polarizer and the liquid crystal panel from external ultraviolet rays, an ultraviolet absorber may be added to the copolymer resin. Although the kind of ultraviolet absorber is not specifically limited, The use of a benzotriazole type ultraviolet absorber and a triazine type ultraviolet absorber is preferable. Preferably Tinuvin P and Tinuvin 360 can be used. As the heat stabilizer, Iganox 259, Iganox 1010, or the like may be added.

Since the optical film including the copolymer as described above is manufactured using a copolymer resin having high light transmittance, glass transition temperature and toughness, the optical film has high optical transparency and excellent adhesion due to the high content of monomer having polar functional groups. Therefore, it is suitable for use as a laminated film such as a polarizing plate. In addition, the optical film according to the present invention not only has excellent optical properties, but also changes in dimensional change rate and optical properties according to temperature and humidity, and thus can be used as various optical films.

It is preferable that the thickness of the optical film which concerns on this invention is 20-200 micrometers.

The optical film according to the present invention can modify the surface of the film to improve adhesion. Modification methods include a method of treating the surface of the film by corona treatment, plasma treatment, UV treatment, and the like, and a method of forming a primer layer on the surface of the film. The above two methods may be used simultaneously. Although the kind of primer is not specifically limited, It is preferable to use the compound which has a reactive functional group like a silane coupling agent.

The present invention also includes a polarizer and a protective film provided on at least one surface of the polarizer, the protective film provides a polarizing plate, characterized in that the optical film containing the copolymer described above.

In the present invention, as the polarizer can be used without limitation what is known in the art, for example, a film made of polyvinyl alcohol (PVA) containing iodine or dichroic dye can be used. The polarizer may be prepared by dyeing iodine or dichroic dye on the PVA film, but a method of manufacturing the same is not particularly limited. In the present specification, the polarizer means a state not including a protective film, and the polarizing plate means a state including a polarizer and a protective film.

Adhesion of the polarizer and the protective film may be performed using an adhesive layer. The adhesive usable in lamination of the protective film and the polarizing plate is not particularly limited as long as it is known in the art. For example, there are one- or two-component polyvinyl alcohol (PVA) adhesives, polyurethane adhesives, epoxy adhesives, styrene butadiene rubber (SBR) adhesives, and hot melt adhesives, but are not limited to these examples.

Among the adhesives, a polyvinyl alcohol adhesive is preferable, and in particular, it is preferable to use an adhesive containing a polyvinyl alcohol resin containing an acetacetyl group and an amine metal compound crosslinking agent. The adhesive for the polarizing plate may include 100 parts by weight of the polyvinyl alcohol-based resin containing the acetacetyl group and 1 to 50 parts by weight of the amine-based metal compound crosslinking agent.

The polyvinyl alcohol-based resin is not particularly limited as long as it can sufficiently adhere the polarizer and the transparent protective film, have excellent optical transparency, and there is no change in yellowing over time, but in particular, considering a smooth crosslinking reaction with a crosslinking agent, It is preferable to use polyvinyl alcohol-type resin containing an acetacetyl group.

Here, the polymerization degree and saponification degree of the polyvinyl alcohol-based resin is not particularly limited as long as it contains an acetacetyl group. Preferably, the polymerization degree is in the range of 200 to 4,000, and the saponification degree is 70 mol% to 99.9 mol%. It is good to be in range. Considering the flexible mixing with the containing material according to the freedom of molecular movement, the degree of polymerization is in the range of 1,500 to 2,500, and the degree of saponification is more preferably in the range of 90 mol% to 99.9 mol%. In this case, the polyvinyl alcohol-based resin preferably comprises 0.1 to 30 mol% of the acetacetyl group. This is because the reaction with the crosslinking agent may be smooth in the range of the acetacetyl group, and sufficiently pays attention to the water resistance and adhesion of the desired adhesive.

The amine-based metal compound crosslinking agent is a water-soluble crosslinking agent having a functional group having reactivity with the polyvinyl alcohol-based resin, and is preferably in the form of a metal complex containing an amine ligand. Possible metals include zirconium (Zr), titanium (Ti), hafnium (Hf), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), osmium (Os), Transition metals such as rhodium (Rh), iridium (Ir), palladium (Pd), and platinum (Pt) are possible, and ligands bound to the central metal are primary amines, secondary amines (diamines), tertiary amines and ammonium hydrides. It is possible to include at least one or more amine groups, such as locksides. Its amount is preferably adjusted in the range of 1 part by weight to 50 parts by weight based on 100 parts by weight of the polyvinyl alcohol-based resin. This is because it is possible to impart sufficiently significant adhesive strength to the desired adhesive within the above range, and to improve the pot life of the adhesive.

PH of the aqueous solution containing the polyvinyl alcohol-based resin containing the acetacetyl group and the amine-based metal compound crosslinking agent as the adhesive for the polarizing plate may be 9 or less.

Here, it is preferable that the pH of the adhesive aqueous solution containing the polyvinyl alcohol-based resin containing the acetacetyl group and the amine-based metal compound crosslinking agent is adjusted to 9 or less using a pH adjusting agent. More preferably, the pH can be adjusted in the range of 2 seconds and 9 or less, and more preferably in the range of 4 to 8.5.

The adhesion of the polarizer and the protective film is first coated with an adhesive using a roll coater, a gravure coater, a bar coater, a knife coater, or a capillary coater on the surface of a polarizing film or a PVA film that is a polarizing film. Before the completely dried, the protective film and the polarizing film may be carried out by a method of laminating by heating or pressing at room temperature with a lamination roll. In the case of using a hot melt adhesive, a heat press roll should be used.

When using a polyurethane adhesive, it is preferable to use the polyurethane adhesive manufactured using the aliphatic isocyanate compound which is not yellowed by light. When using one-component or two-component dry laminate adhesives or adhesives with relatively low reactivity between isocyanates and hydroxyl groups, a solution-type adhesive diluted with an acetate solvent, a ketone solvent, an ether solvent, or an aromatic solvent, etc. You can also use At this time, the adhesive viscosity is preferably low viscosity of 5000 cps or less. The adhesives are excellent in storage stability and preferably have a light transmittance of 90% or more at 400 to 800 nm.

A tackifier can also be used if it can exert sufficient adhesive force. The adhesive is preferably cured by heat or ultraviolet rays after lamination, and thus the mechanical strength is improved to the level of the adhesive. The adhesive strength is also large, and thus the adhesive strength is such that the adhesive cannot be peeled off without breaking of either film to which the adhesive is attached. It is preferable.

Specific examples of the pressure-sensitive adhesives that can be used include natural rubber, synthetic rubber or elastomer having excellent optical transparency, a vinyl chloride / vinyl acetate copolymer, polyvinyl alkyl ether, polyacrylate, modified polyolefin-based pressure-sensitive adhesive, and a curing type in which a curing agent such as isocyanate is added thereto. An adhesive is mentioned.

The polarizing plate of the present invention manufactured as described above can be used in various applications. Specifically, it can be preferably used for an image display device including a polarizing plate for liquid crystal display (LCD), an anti-reflective polarizing plate of an organic EL display device, and the like. In addition, the polarizing plate according to the present invention combines various optical layers such as retardation plates, light diffusing plates, viewing angle expanding plates, brightness enhancing plates, reflecting plates such as various functional films, for example, λ / 4 plates, λ / 2 plates, and the like. It can be applied to one composite polarizer.

The polarizing plate according to the present invention may be provided with a pressure-sensitive adhesive layer on at least one surface so as to be easily applied to an image display device. In addition, a release film may be further provided on the pressure-sensitive adhesive layer to protect the pressure-sensitive adhesive layer until the polarizing plate is applied to an image display device or the like.

In addition, the present invention provides an image display device including the polarizing plate.

For example, the present invention includes a light source, a first polarizing plate, a liquid crystal cell, and a second polarizing plate sequentially stacked, and at least one of the first and second polarizing plates is provided on at least one surface of the polarizer and the polarizer. A film, wherein the protective film comprises 0.1 to 30 mol% of at least one alkene monomer, 30 to 99 mol% of at least one acrylate monomer, and 0.1 to 50 mol% of at least one styrene monomer. It provides a liquid crystal display device, characterized in that the polarizing plate, characterized in that the optical film containing a copolymer. The liquid crystal cell is a liquid crystal layer; A substrate capable of supporting this; And an electrode layer for applying a voltage to the liquid crystal. At this time, the polarizing plate according to the present invention is an in-plane switching mode (IPS mode), vertically aligned (VA mode), OCB (Optically Compensated Birefringence mode), twisted nematic mode (Twisted Nematic mode) TN mode) and FFS (Fringe Field Switching mode; FFS mode).

In the image display apparatus according to the present invention, the optical film according to the present invention may be disposed as an inner protective film on the liquid crystal cell side of the polarizing plate and / or at the same time as an outer protective film on the opposite side of the liquid crystal cell of the polarizing plate.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only for illustrating the present invention and the scope of the present invention is not limited to the contents of the following examples.

The organic reagents and solvents required for the polymerization were purified by a standard method by Aldrich, and ethylene was polymerized after passing a high purity product of Applied Gas Technology through a water and oxygen filtration device.

In order to obtain a monomer content ratio in the copolymer, spectra were obtained using 500 MHz NMR manufactured by Varian. The glass transition temperature (Tg), which is a thermal property of the obtained polymer, was measured by DSC Q100 from TA Instrument, and Td_50 (50% pyrolysis temperature) was used as TGA of the same company.

Molecular weight and molecular weight distribution were obtained by gel permeation chromatography (GPC) analysis from Waters. The analytical temperature was 25 ° C., tetrahydrofuran (THF) was used as the solvent, and standardized with polystyrene to obtain the number average molecular weight (Mn) and the weight average molecular weight (Mw).

Using Axometrics' Polarimeter (Axoscan), the planar retardation (Rin) and thickness retardation (Rth) of the prepared optical film were measured. Each retardation is defined by the following equation.

Rin = (nx-ny) x d, Rth = (nz-ny) x d

Here, nx, ny, nz means refractive index in each direction, and d means the thickness of a film. The birefringence was measured by the above method.

Transparency was measured by measuring the transparency in the wavelength range 200 ~ 1000nm with a UV meter (Agilent 8453) by making a specimen in a film 2cm in length and length.

Elongation was measured using a universal tensile tester (Instron, M 4202) according to ASTM D638.

Comparative Example 1

The 125 mL high pressure reactor was evacuated and filled with argon. 28 mmol of styrene was added to the reactor in the argon atmosphere. And 0.059 mmol of initiator AIBN dissolved in toluene was added. The reactor temperature was then raised to 75 ° C. at atmospheric pressure and polymerization was carried out for 18 hours.

Comparative Example 2

Polymerization was carried out in the same manner as in Comparative Example 1 except that instead of 28 mmol of styrene, 14 mmol of styrene, 14 mmol of methyl methacrylate, and 11.2 mmol of alumina were added thereto.

Comparative Example 3

The 125 mL high pressure reactor was evacuated and filled with argon. 28 mmol of styrene was added to the reactor in the argon atmosphere. And 0.056 mmol of initiator AIBN dissolved in toluene was added. Subsequently, after charging 35 bar of ethylene, the reactor temperature was raised to 75 ° C. and polymerization was performed for 18 hours.

The polymerization conditions and results of Comparative Examples 1 to 3 are shown in Tables 1 to 3.

Polymerization Conditions of Comparative Examples 1 to 3 Reaction dosage Polymerization conditions [menstruum]
/ [Monomer] (volume ratio) [Mountain Lewis]
/ [MMA]
(mole rain) [Initiator]
/ [Monomer]
(mole rain) [Styrene]
/ [MMA]
(mole rain) Ethylene
pressure
(bar) Temperature (℃) Time (h) Comparative Example 1 3 0 0.0021 0 0 75 18 Comparative Example 2 3 0.8 0.0021 One 0 75 18 Comparative Example 3 15 0 0.002 0 35 75 18

In Table 1, [monomer] means the volume or number of moles of styrene or styrene + MMA.

Polymer Compositions and Physical Properties Prepared in Comparative Examples 1 to 3 Polymer composition Polymer property Styrene
content
(mole%) MMA
content
(mole%) Ethylene
content
(mole%) Tg
(℃) Mn Mw PDI Td_50
(℃) Comparative Example 1 100 0 0 103.5 27000 45400 1.68 447.6 Comparative Example 2 51 49 0 103.8 22900 38800 1.69 426.7 Comparative Example 3 92 0 8 91.4 9720 16000 1.64 Unmeasured

Birefringence, Transparency and Elongation Prepared in Comparative Examples 1 to 3 Re _th (nm) transparency(%) Elongation (%) Comparative Example 1 -103 76 One Comparative Example 2 -97 85 2 Comparative Example 3 -100 77 12

Example 1

The 125 ml Parr high pressure reactor was evacuated and filled with argon. 28 mmol of methyl acrylate (MMA), 28 mmol of styrene, and 22.4 mmol of alumina were charged into an argon atmosphere reactor. And 0.118 mmol of initiator AIBN dissolved in toluene was added. Subsequently, after charging 35 bar of ethylene, the reactor temperature was raised to 75 ° C. and polymerization was performed for 18 hours.

After the polymerization was completed, the polymerization solution was removed alumina through a filter, and precipitated in hexane. The polymer obtained by filtration was dried at 80 ° C. at a temperature of Tg or lower under reduced pressure (Vacuum Oven) for 24 hours.

Examples 2-4

The polymerization was carried out in the same manner as in Example 1, except that the content of the added ingredient was as shown in Table 1 below.

The polymerization conditions and results of Examples 1 to 4 are shown in Tables 4 to 6.

Polymerization Conditions in Examples 1-4 Reaction dosage Polymerization condition [menstruum]
/ [Monomer]
(Volume ratio) [Styrene]
/ [MMA]
mole rain) [Mountain Lewis]
/ [MMA]
(mole rain) [Initiator]
/ [Monomer]
(mole rain) Ethylene
pressure
(bar) Temperature
(℃) time
(h) Example 1 15 One 0.8 0.0021 35 75 18 Example 2 15 0.5 0.8 0.0021 35 75 18 Example 3 15 0.25 One 0.002 35 75 18 Example 4 15 0.2 One 0.002 35 75 18

[Monomer] in Table 4 means the volume or mole number of styrene + MMA.

Polymer Compositions and Physical Properties of Examples 1 to 4 Polymer composition Polymer property Styrene
content
(mole%) MMA
content
(mole%) Ethylene
content
(mole%) Tg
(℃) Mn Mw PDI Td_50
(℃) Example 1 42 46 12 94.4 16600 25200 1.52 438 Example 2 32 53 15 90.4 16800 25300 1.51 Unmeasured Example 3 25 67 8 96.3 21500 33800 1.57 Unmeasured Example 4 27 73 5 101.1 31400 45300 1.44 Unmeasured

Birefringence, Transparency and Elongation Prepared in Examples 1 to 4 Re _th (nm) transparency(%) % Elongation Example 1 -90 87 22 Example 2 -78 88 27 Example 3 -69 88 13 Example 4 -68 90 10

Claims (19)

0.1 to 30 mol% of at least one alkene monomer, 30 to 99 mol% of at least one acrylate monomer, and 0.1 to 50 mol% of at least one styrene monomer, wherein the alkene monomer is 1-alkene, Copolymer comprising at least one selected from the group consisting of 2-alkenes, 3-alkenes and cyclic olefins. The copolymer according to claim 1, wherein the glass transition temperature (Tg) is in a range of 80 to 220 ° C. The copolymer according to claim 1, wherein the number average molecular weight is 5,000 to 400,000, and the weight average molecular weight is 10,000 to 800,000. The copolymer according to claim 1, wherein the temperature (Td ₅₀ ) at which 50% of the initial weight is decomposed is in the range of 300 to 550 ° C. delete The copolymer of claim 1, wherein the acrylate-based monomer comprises a compound of Formula 2 [Formula 2]

In Chemical Formula 2, R ₁₁ , R ₁₂ and R ₁₃ are the same as or different from each other, and each independently represent a hydrogen atom, a monovalent hydrocarbon group having 1 to 30 carbon atoms which may include a hetero atom; R ₁₄ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. The copolymer of claim 1, wherein the styrene monomer is at least one selected from the group consisting of methyl styrene, ethyl styrene, propyl styrene, butyl styrene, pentyl styrene, hexyl styrene, fluoro styrene, and styrene chloride. 0.1 to 30 mol% of at least one alkene monomer selected from the group consisting of 1-alkenes, 2-alkenes, 3-alkenes and cyclic olefins, 30 to 99 mol% of at least one acrylate monomer and at least one A method for producing a copolymer comprising the step of polymerizing 0.1 to 50 mol% of a styrene monomer with a radical polymerization initiator in the presence of a metal oxide. delete The method of claim 8, wherein the metal oxide is a compound represented by Formula 3 below: (3) M _x N _y O _z In Chemical Formula 3, M represents at least one selected from the group consisting of alkaline earth metals, transition metals, group 13, and group 14 metals; N represents a Group 5 or 6 atom; O represents an oxygen atom; x, y and z are values determined by the oxidation state of M and N, x> 0, y> 0, and z> 0. The method of claim 8, wherein the metal oxide is used in an amount of 0.01 to 200 mol% based on the acrylate-based comonomer. The method of claim 8, wherein the radical polymerization initiator is added in an amount of 0.01 to 1 mol% based on the acrylate monomer. The method according to claim 8, wherein the polymerization is carried out under conditions of 200 atm and 150 ° C or less. An optical film comprising the copolymer according to any one of claims 1, 2, 3, 4, 6 or 7. The optical film of claim 14, wherein at least one surface is treated to improve adhesion. The optical film of claim 15, wherein the treatment comprises at least one selected from corona treatment, plasma treatment, UV treatment, and primer layer formation. And a protective film provided on at least one surface of the polarizer and the polarizer, wherein the protective film is an optical film according to claim 14. An image display device comprising the optical film of claim 14. An image display device comprising the polarizing plate of claim 18.